The invention relates generally to digital mobile communication systems and more particularly to providing data service in a mobile communication system.
Mobile communication systems refer, in general, to different telecommunication systems providing personal wireless data transmission while subscribers roam the system area. A typical mobile communication system is the public land mobile network PLMN.
Besides conventional speech transmission, digital mobile communication systems provide a plurality of other services: short messages, facsimiles, data transmission, etc. Of these, the data transmission service, in particular, provides a mobile subscriber a chance of wireless access to nearly all data services of fixed networks.
The use of the Internet data network in fixed networks has increased very rapidly. As is well known, the Internet network actually comprises a large number of smaller interconnected networks. Data transmission in Internet is packet-switched in accordance with the TCP/IP protocol (Transmission Control Protocol/Internet Protocol). The growing popularity of Internet is primarily due to a system called World Wide Web (WWW). The WWW system consists of servers in the Internet network and customer programs used by these servers, called WWW browsers. The information in the WWW servers is arranged into pages which are the basic units of the WWW technique, as whole pages are always transferred between a server and a browser. In addition to text, the page may also contain graphics and various other file types, such as voice and video. The pages used by the WWW technique are described with the HTML language (Hyper Text Mark-up Language). Information on text format, graphics, etc. is coded among the actual text contents by HTML tags. The browser program uses these tags to give a WWW page the desired format.
There is a connection between a WWW server and a user only during the transfer of a WWW page to a user. This means that when requesting a WWW page, a user sends a transfer request to a WWW server which sends the requested page back via the line. Transfer requests and WWW pages are transferred by the HTTP protocol (Hyper Text Transfer Protocol). The receiver's browser program restores the WWW page received into the right form in accordance with the HTML language. A transferred WWW page is stored in the memory of the user's computer, the user being able to browse the page on his/her own screen. The addressing format of the Internet WWW servers is URL (Uniform Resource Locator).
Through the data transmission services of mobile communication systems, the numerous information sources of the Internet network are, in principle, available to mobile subscribers, too. However, the use of data transmission services typically requires a mobile station provided with data transmission properties, and a computer connected thereto. At present, mobile stations including an integrated computer, such as the Nokia Communicator, are available. However, these are relatively expensive alternatives and hence not suitable to occasional usage by an ordinary mobile subscriber.
The Internet network, however, offers numerous information sources which could be useful to an ordinary user, too. These could include e.g. flight, train, bus schedules, weather and traffic reports, telephone number and address information etc. At present, most of these services are free of charge and available to everybody. Internet is also commonly used in companies for internal services. Thus it would be advantageous to render the various information sources offered by Internet available to users of mobile stations without any data transmission facilities.